Around 6pm, the helicopter crashed on the Mull of Kintyre killing all 25 passengers and 4 crewmen.
Naturally, the nature of those on board led to instant speculation about the cause of the crash. While investigations at first blamed pilot error, a later reopened investigation cleared the pilots and focussed on software problems that were known to have plagued the RAF's Chinook fleet at the time (2 aircraft were withdrawn from service on the 31st May for this reason). To some eyes, these explanations remain too anodyne, given the political importance of the people on board.
It is rumoured among the conspiracy-minded that the helicopter was, in fact, headed to RAF Macrihanish for some suspected clandestine purpose. Another rumour favoured among a certain branch of conspiracist thought is that the Chinook was somehow brought down by the supposed 'Aurora' spy plane. This allegation was taken seriously enough to reach the pages of the British technology magazine The Register in 2000, who told their readers that:
"...a third explanation for the crash has now come to light: that a top secret hypersonic US plane, codenamed Aurora and which is reportedly capable of flying at up to 20 times the speed of sound, created a massive jet wake into which the helicopter flew, causing the crew to lose control."
Another theory holds that the 'copter was deliberately brought down as part of a political pincer movement to expedite movements in the political situation in Northern Ireland - with several of those who died being seen as obstacles to progress of one kind or another in the province (the machinations seem too exhausting to recount at the time of writing but the 'operation' was either a total success or desperate failure depending on the perspective you take).
In truth, with black boxes not routinely fitted to the Chinook fleet until 2002 the events of the crash will probably remain impossible to comprehensively pinpoint - although a combination of pilot fatigue and instrument/software error seem most likely. But in the absence of solid facts, conspiracy finds an easy place to grow and given the instrinsically shady nature of military intelligence's operations will prove impossible to disprove.
See also: conspiracy theories